The long-range goal of this research is to enhance our understanding of how gender is related to the pain experience of individuals having arthritis. Research studies conducted in the laboratory of the principal investigator and elsewhere have shown that women with osteoarthritis (OA) report more intense pain and more severe disability. To date, the basis of this gender difference has been unknown. Preliminary research by the principal investigator suggests that differences in coping may account for gender differences in pain and disability in OA. Three new studies are proposed. Study 1 uses newly developed daily study methods to examine pain, pain coping, and mood as they unfold both within and across days in men and women having knee OA. In this study, 110 patients having knee OA (55 men, 55 women) will keep daily diary records for 30 consecutive days. Each patient will provide two daily diary entries on their pain, pain coping strategies, and mood. This process-oriented research design will permit the examination of: (a) gender differences in the extent and patterning of OA pain and efforts to cope with pain; and (b) how women and men differ in the relations of coping to pain, and mood both within and across days. Studies 2 and 3 will examine the relationship between gender differences in emotion-focused coping and supraspinal modulation of a nocifensive spinal withdrawal reflex known as the nociceptive flexion reflex (NFR). Study 2 will assess the NFR threshold and subjective pain threshold and tolerance levels of 66 men and 66 women having OA knee pain. Study 3 will assess potential gender differences in activation of supraspinal descending pain modulation systems. This study will examine the nociceptive flexion reflex at rest and during a distraction task designed to manipulate attentional focus.